Temperature and Humidity Sensor Node Design
Make me a temperature and humidity sensor node with Wifi and Bluetooth, powered by USB-C (5V) for consumer use.
It should be a low-power environmental node with a digital T/RH sensor, ultra-low-power MCU with Wi-Fi + Bluetooth (dual-radio) — 2.4 GHz 802.11 b/g/n plus BLE 5.x powered by USB-C (5 V) — USB-C receptacle 5 V default; include reverse/OVP/UVLO/OCP protection and plan for 0.5–3 A sources.
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High-Level Execution Plan
Project Scope
Consumer low-power environmental sensor node with Wi-Fi + Bluetooth, USB-C 5V power input, digital temperature/humidity sensing, and robust front-end protection for a wide range of USB-C source capabilities.
Major Implementation Phases
1. Define System Architecture
- Establish the top-level functional blocks: USB-C power entry, input protection/power conditioning, regulated system power, MCU + wireless subsystem, temperature/humidity sensing, programming/debug, and optional status indication.
- Define the operating concept for low-power sensing, wake/sleep behavior, wireless reporting, and expected user interaction.
- Set project-level targets for power budget, boot behavior, protection response, and environmental operating assumptions.
2. Power Entry and Protection Strategy
- Define the USB-C 5V sink interface for default 5V operation across compliant USB-C sources.
- Architect the input protection chain to cover:
- reverse polarity / backfeed prevention
- over-voltage protection
- under-voltage lockout
- over-current protection
- tolerance of source capability ranging from 0.5A to 3A
- Establish system behavior for brownout, hot-plugging, cable transients, and fault recovery.
3. Low-Power Processing and Wireless Subsystem
- Select and integrate the ultra-low-power MCU platform with integrated 2.4 GHz 802.11 b/g/n Wi-Fi and BLE 5.x.
- Partition always-on versus switchable power domains where needed.
- Define clocking, reset, boot/programming access, RF keepout needs, antenna placement constraints, and firmware update strategy.
4. Sensor Subsystem Definition
- Integrate the digital temperature/humidity sensing block and its interface to the MCU.
- Define sensor placement goals to improve measurement quality and reduce self-heating or RF/power-circuit influence.
- Establish filtering, pull-up/interface needs, and any calibration or data-quality considerations.
5. Power Budget and Operating Modes
- Define major operating states: plug-in/startup, idle, measurement, advertise/connect, Wi-Fi transmit, and fault states.
- Build a high-level current-consumption model for each mode.
- Validate that regulator strategy, thermal limits, and USB-C source assumptions support peak and average consumption goals.
6. Schematic Capture and Design Rules
- Capture the system schematic by block, starting with power entry/protection, then processing/wireless, then sensing and support circuitry.
- Apply naming conventions, net labeling, decoupling strategy, protection annotations, and test/debug access.
- Run ERC/review checks early and iterate before layout begins.
7. PCB Floorplanning and RF-Aware Layout
- Define board outline constraints and connector placement.
- Floorplan the PCB around critical zones: USB-C entry, protection path, regulators, RF module/antenna keepout, sensor location, and debug/test access.
- Prioritize return paths, decoupling placement, noise isolation, thermal relief, and antenna edge placement / keepout requirements.
8. Verification and Bring-Up Plan
- Verify power-path behavior, protection thresholds, startup sequencing, reset stability, sensor communications, and radio functionality.
- Prepare a staged bring-up flow: input power validation first, rails second, MCU programming third, sensor readout fourth, wireless connectivity last.
- Define basic bench tests for fault handling, current draw, and communication reliability.
9. Firmware and System Integration
- Establish minimal firmware milestones: boot, sensor read, BLE advertisement, Wi-Fi connectivity, data packaging/reporting, low-power sleep/wake, and fault monitoring.
- Align firmware assumptions with hardware interfaces, pin mapping, and power-state control.
- Plan early diagnostics and telemetry hooks to support bring-up.
10. Final Review for Consumer Readiness
- Review the design for robustness, manufacturability, user safety, connector usability, and environmental sensing performance.
- Confirm the protection architecture, low-power behavior, RF/layout constraints, and test strategy are all represented in the final design package.
Project Scope
Major Implementation Phases
1. Define System Architecture
2. Power Entry and Protection Strategy
3. Low-Power Processing and Wireless Subsystem
4. Sensor Subsystem Definition
5. Power Budget and Operating Modes
6. Schematic Capture and Design Rules
7. PCB Floorplanning and RF-Aware Layout
8. Verification and Bring-Up Plan
9. Firmware and System Integration
10. Final Review for Consumer Readiness
